Prediction of the Kováts retention indices of thiols by use of quantum chemical and physicochemical descriptors

Quantum chemical and physicochemical descriptors of thiols have been obtained by PM3 Hamiltonian calculation. The thiols included linear, branched, cyclic, saturated, and unsaturated compounds with thiohydroxy groups on primary, secondary, or tertiary carbon atoms. Models of quantitative structure-retention relationships for the thiols on the stationary phases Apiezon M, OV-17, Triton X-305, and PEG 20M were established by both forward and backward stepwise regression techniques. The multiple correlation coefficients for the four models were all larger than 0.9996. The stability and validity of the models were tested by external validation testing and by comparing calculated retention indices with experimental data. The linear correlation coefficients between predicted and experimental values were all larger than 0.9968 for both training set and prediction set.